What's new?
Homepage What's new? Biology Distribution Identification Conservation Genetic Study Literature Links How you can help Picture Gallery Contact Us	Establishing the UK's first, new population of D. plantarius in the wild One of the aims of the Biological Action Plan for Fen Raft Spiders in the England is to reduce their vulnerability by establishing sustainable, new populations in the wild. In 2010 the first steps were taken to establish the first of these populations (click here to view the Action Plan and here to view the revisions that followed the 2005 BAP review). In 2010, the BBC Wildlife Fund supported an experiment to determine the best provenance of spiders to use for establishing these populations - from one or other of the two English populations, or hybrids between them. Although increasing genetic diversity by combining the these two long-isolated populations might be expected to result in offspring that are better able to adapt to their new environment and to future environmental change (hybrid vigour), there are circumstances in which such hybrids can be less successful (outbreeding depression). It was important to ensure that new populations established by deliberate translocation stand the best possible chance of long-term success. Sub-adult spiders from the Sussex Wildlife Trust's nature reserve on the Pevensey Levels and the Suffolk Wildlife Trust's Redgrave and Lopham Fen nature reserve were matured in captivity and paired both within and between populations. The resulting offspring - from 18 successful parings - were reared in captivity for ca 15 weeks and their survival and growth rates monitored. Preliminary results showed that the hybrids were at least as successful as the within-populations crosses and so Natural England decided that the spiderlings from the experiment should be used to found the first new population. The Steering Group for the project, which has evaluated all aspects of the translocation against established codes of practice, approved release of the hybrid spiderlings at the Suffolk Wildlife Trust's reserve at Castle Marshes in October. This internationally important area of grazing marshes is on the River Waveney, downstream from the spider's East Anglian site at Redgrave and Lopham Fen at the source of the river. It is highly likely that this species occurred in this area in the past but was lost when the quality of the dykes was degraded by conversion of the marshes to arable agriculture. The dykes have now been restored and support a rich assemblage of invertebrates and plants, very similar to those on the Pevensey Levels, the spider's stronghold on the south coast of England. In addition to releasing over 1,500 spiderlings at Castle marshes, over 2000 spiderlings of single site provenance were returned to their natal populations, on the the Pevensey Levels, and at Redgrave and Lopham Fen. At the latter site they were used not only to boost numbers in the two small areas to which they had become confined, but also to create a new, third focus for the population within the nature reserve. Although habitat restoration by the Suffolk Wildlife Trust at this site over the last decade has been very successful, the spiders have failed to recolonise ideal new areas. Translocating them within the reserve, in addition to creating chains of new turf ponds and scrapes linking the sub-populations, is expected to aid recolonisation of extensive areas of the reserve. In future years, the possibility of boosting depleted genetic diversity at Redgrave and Lopham Fen by introducing spiders from the Pevensey Levels will be evaluated. Spider-rearing in Suffolk kitchen.... UK media attention was briefly diverted from the gloom of the UK Government's Comprehensive Spending Review in October by the story of the spiderling release at Castle Marshes. National as well as local radio channels and newspapers picked up this good news story in the International Year of Biodiversity. The fact that the spiderlings parents had been mated, and most of the spiderlings hatched and reared in a domestic kitchen added human interest to the story! Some of the spiderlings were reared in a conventional laboratory setting at the Insectory at the John Innes Centre in Norwich but most lived in Helen Smith's kitchen where she reared them individual test tubes (to avoid cannibalism) and fed them on an abundant supply of fruitflies from the garden compost bins. The news story traveled around the world, not only via the BBC and national newspaper websites, but also reaching newspapers in Iceland, the Netherlands and Paris. It's good to know that small spiders can make big news! Click on the links to read the Press releases issued by Natural England and the Suffolk Wildlife Trust. View coverage on the BBC website. Read newspaper coverage of the story: The Daily Telegraph The Guardian The Daily Mail The East Anglian Daily Times The Eastern Daily Press The Diss Mercury The Diss Express The Lowestoft Journal and from Iceland... Posted 11-2010 Artist's Residency In this ground-breaking project D.plantarius has become the UK's first spider to have its own artist in residence! Arts Council England awarded a grant to Yorkshire artist Sheila Tilmouth to work alongside the D. plantarius conservation project at Redgrave and Lopham Fen during summer 2009 and the BBC Wildlife Fund continued to fund the project in 2010. The residency has been supported by the Suffolk Wildlife Trust, Buglife, The British Arachnological Society and the Natural History Museum. It aims to bring the story of this spectacular spider, and the more general messages it conveys about the amazing lives of spiders and the plight of wetland species, to a new, wider audience. Click here to read Sheila's blog and see some of her work on D. plantarius. Sheila Tilmouth's work was exhibited at the Visitor Centre at Redgrave and Lopham Fen in 2001 and at the Suffolk ildlife Trust's Calton Marshes Education Centre in October 2010. Watch this space for future venues for the exhibition. Spot the Spider! This web challenge, to pinpoint individuals of D. plantarius photographed against their natural backgrounds, produced over 2,000 responses in the first month. It is part of a project on the colour banding polymorphism in this species, investigating the genetic basis of the polymorphism and reasons for its persistence. To play 'spot the spider' click here, and for more information on the project click here. Posted 09-2009 British Arachnological Society survey work in 2009 Throughout summer 2009 voounteers from the British Arachnological Society (BAS) have been helping with the search for hitherto undiscovered UK populations of D. plantarius. Survey work has covered potentially appropriate sites in the Norfolk and Suffolk Broads, the chalk stream fens of Hamshire and the south coast grazing marshes. This work forms part of an evaluation of the need to translocate this species to new sites to ensure its future in the UK. Although no new D. plantarius populations were discovered, the surveys generated some exciting records of other species, mostly notably of Enoplognatha tecta (E. caricis) from a Suffolk site. This is only the third UK record for this wetalnd species, the others being from a Dorset site in 1888 and 1974. Drought grips Redgrave and Lopham Fen The severe late summer 2009 drought in East Anglia left the D. plantarius population at Redgrave and Lopham Fen virtually without standing water for over six weeks. Although the hydrology of this National Nature Reserve was restored in 1999 by by ending artesian abstraction from the underlying chalk aquifer (click here for further information), it remains very vulnerable to drought. Drought curtails the spider's breeding season and reduces growth rates. This in turn results in the porduction of smaller broods of young the following year. This is the third severe drought to hit the fen since 1999. It raises concerns about the long-term future of the spider at this site if, as predicted, the frequency and severity of summer droughts increases. The Suffolk Wildlife Trust, which manages the reserve, have obtained funding through the HLS Scheme to deepen some of the existing ponds and create chains of new ponds radiating out from the existing centres of the spider population. It is hoped that this will both safeguard the population during summer droughts and encourage range expansion into areas that have suitable vegetation but have been without suitable ponds. New Dolomedes plantarius populations discovered in continental Europe We have heard of the discovery of three new populations of D. plantarius in 2009, near Lake Maggiore in northern Italy, in the Savoy in France, and on a lake in the centre of the Swedish city of Jönköping. For more information on the distribution of this species, click here. Back to top of page
	HOMEPAGE
	This site is maintained by Helen Smith
	Last updated 16 October 2009